As an electromagnetic contactor, there is known a device of, e.g., Patent Document 1.
In the electromagnetic contactor of Patent Document 1, there are accommodated in a case, an electromagnet, a movable contact support disposed in parallel with the electromagnet, a return spring urging the movable contact support toward an initial position, and a drive lever which transmits an attraction movement and a release movement of the electromagnet to the movable contact support.
The movable contact support includes a plurality of movable contacts, moves against the return spring, and performs an opening and closing operation with fixed contacts disposed in the case so as to face the individual movable contacts. The electromagnet includes an exciting coil, a fixed core, and a movable core which is disposed to face the fixed core so as to be movable close to or away from the fixed core.
The drive lever is an elongated plate-like member, and is formed with arm portions in the central portion in a longitudinal direction, and a protrusion on one side surface of one end portion in a plate thickness direction.
One end portion of the drive lever is inserted into an insertion hole of the movable contact support, the arm portions thereof abut on a receiving surface formed on an opening peripheral edge of the insertion hole, and the drive lever is thereby engaged with the movable contact support. Further, the drive lever is assembled in a state where one end portion is inserted into a loose-fitting hole formed in the movable core, the protrusion formed at one end portion is contacting with an inner surface of the loose-fitting hole which is farthest from the fixed core, and the other end portion is engaged with a receiving groove formed in an inner wall of an upper case which faces the movable core via the movable contact support.
When the exciting coil of the electromagnet is brought into an excited state and the movable core of the electromagnet is attracted by the fixed core, the movement of the movable core by the attraction is transmitted to the drive lever via the protrusion at one end portion, and the drive lever rotates about the other end portion engaged with the receiving groove of the upper case, whereby the rotation of the drive lever is transmitted to the movable contact support as a predetermined stroke, the movable contact support moves from the initial position to an operation position, and the opening and closing operation of the individual movable contacts and the corresponding fixed contacts is performed.
Patent Document 1: Japanese Patent publication No. S64-48339 (FIGS. 1 and 2)
The drive lever of Patent Document 1 has directivity at the time of assembly that the drive lever is assembled in the state where the protrusion formed at one end portion is in contact with the inner surface of the loose-fitting hole formed in the movable core which is farthest from the fixed core.
However, even when the assembly of the drive lever of Patent Document 1 is performed in a state where the drive lever is oriented in the opposite direction in which the protrusion at one end portion does not abut on the inner surface of the loose-fitting hole (hereinafter referred to as incorrect assembly), the drive lever can be attached into an electromagnetic contactor, and therefore the incorrect assembly of the drive lever may impair the normal operation of the electromagnetic contactor.
That is, in the drive lever of Patent Document 1, there are formed a pair of arm portions which protrude outward in mutually opposite directions from end portions in a plate width direction at the same positions (the central portion) in the longitudinal direction and, even when the incorrect assembly of the drive lever is performed with the pair of arm portions disposed in a direction opposite to that in the correct assembly and caused to abut on the receiving surface of the insertion hole, the drive lever can be attached into the electromagnetic contactor.
In the drive lever assembled by the incorrect assembly, since the protrusion at one end portion does not contact with the inner surface of the loose-fitting hole formed in the movable core which is farthest from the fixed core, the movement operation of the movable core of the electromagnet may not be transmitted to the movable contact support as the predetermined stroke, and the opening and closing operation of the movable contacts and the fixed contacts may not be performed normally in the electromagnetic contactor having the drive lever assembled by the incorrect assembly.